In recent years, LED bulbs which can take the place of incandescent bulbs have been widely spreading. LED bulbs, for example as shown in PLT 1, are provided with roughly conical shape cases made of aluminum alloy continuing from caps which are connected to sockets, have boards on which a large number of LED chips are arranged and have electrical circuits inside the cases, and have glass globes fit into the open ends of the cases.
Since LED bulbs have electrical circuits embedded in their cases, when turned on, the surfaces of the cases become extremely high in temperature resulting in the danger of children etc. being burned by touching them or causing fires if set near a flammable item. Further, if water enters from the joints of the cases and globes, the LED boards and electrical circuits break down, so use outdoors or in bathrooms or other locations which are exposed to water is not possible. Further, LED bulbs can only emit light to the front sides due to their utilization of LEDs and cannot light up the surroundings of the bulbs as a whole like with incandescent bulbs.